In 1991, Wendy Grossman in the New Scientist criticized the parapsychologist Stephen E. Braude for ignoring evidence of fraud in mediumship. According to Grossman "[Braude] accuses sceptics of ignoring the evidence he believes is solid, but himself ignores evidence that does not suit him. If a medium was caught cheating on some occasions, he says, the rest of that medium's phenomena were still genuine." Grossman came to the conclusion that Braude did not do proper research on the subject and should study "the art of conjuring."
"The picture reading shows me what goes on in the past life and in this life ... So if it shows me she was your guardian angel at one point, she was a guardian angel," she said. She added that the reading wasn't accurate because I had come in with the intention to trick, that the energy I came in with was one about my sister which is what she picked up on, that the whole thing wasn't very "civilized" of me and that she'd be calling other psychics and warning them about me. She told me she's been tested by people who declared their intentions and passed their tests, and offered to give me a reading that would reveal secrets about me that not even my closest friends know. I declined.
A barcode is a series of alternating dark and light stripes that are read by an optical scanner. The organization and width of the lines is determined by the bar code protocol selected. There are many different protocols, such as the prevalent Code 39. Sometimes the digits represented by the dark and light bars are also printed to allow people to read the number without an optical reader.
According to James Randi, a skeptic who has debunked many claims of psychic ability and uncovered fraudulent practices, mediums who do cold readings "fish, suggest possibilities, make educated guesses and give options." Randi has a standing offer of $1 million US dollars for anyone who can demonstrate psychic ability under controlled conditions. Most prominent psychics and mediums have not taken up his offer.
Many 19th century mediums were discovered to be engaged in fraud. While advocates of mediumship claim that their experiences are genuine, the Encyclopædia Britannica article on spiritualism notes in reference to a case in the 19th century that "...one by one, the Spiritualist mediums were discovered to be engaged in fraud, sometimes employing the techniques of stage magicians in their attempts to convince people of their clairvoyant powers." The article also notes that "the exposure of widespread fraud within the spiritualist movement severely damaged its reputation and pushed it to the fringes of society in the United States."